French police found the prosthetic belly in the couple's apartmentGetty

A young mother has been arrested on suspicion of wanting to use a fake pregnancy "belly" to smuggle explosives and carry out a suicide bomb attack, according to French media reports. The 23-year-old woman, said to have converted to Islam, was arrested along with her husband, 35, in Montpellier, southern France.

The couple's home had been searched by police after the pair were detained last week amidst fears over the woman's "growing radicalisation", according to French regional daily Midi Libre. Officers then found a hollowed out prosthetic belly inside their home. It had been covered in tin foil, said to allow items stuffed inside a greater chance of fooling security gates and metal detectors.

A source close to the investigation said the woman claimed she had bought the fake belly on the internet so she could shoplift from department stores and avoid getting caught.

But French counter-terrorism detectives said the couple had "disturbing profiles" and they were now investigating the pair. Officers said they had found material relating to al-Qaeda and Isis (Daesh) on their computers, with the woman also allegedly researching female suicide bombers. According to Midi Libre, she had told her family she wanted "to die a martyr", and had convinced her husband to do the same.

The couple are reportedly being held under house arrest as the investigation continues. Their two-year-old child has also been taken from them.